1. Field of the Invention
The invention generally relates to a method and apparatus for the deacidification of cellulosic materials. More particularly, the invention relates to an improved method for handling the cellulosic materials such as books, magazines, newspapers, documents and the like during the deacidification process.
2. Description of the Invention Background
The deterioration of paper, books and newspapers is wellknown and of growing concern to librarians and archivists throughout the world. The causes of paper deterioration are numerous and include inherent acidity, photodegradation, oxidation, and even microbiological attack under certain conditions. These factors combined with initial paper quality have severely reduced the permanence of library and archival collections.
The demand for large amounts of printing paper over the last century has led to the introduction of pulp fiber produced from wood by chemical or mechanical means. However, paper made from untreated wood pulp is too absorbent to allow sharp image imprint. Therefore, chemicals have to be added to the wood fibers during processing. These additives allow the paper to accept inks and dyes and increase paper opacity. Unfortunately, most of these chemicals are either acidic or are deposited by acidic mechanisms which initiate the slow, but relentless acidic deterioration of paper. Other contributions to the acidification of paper are supplied by man through industrial emissions of sulphur and nitrogen and carbon oxides or by natural processes such as sea salt spray. Even books or paper of neutral and alkaline character are not immune. As neighboring papers of acidic nature degrade, volatile acids are produced which either diffuse through adjoining books or permeate the atmosphere and may ultimately acidify even the "safe or stable" books.
In order to arrest this acidic degradation, paper materials must be deacidified and provided with an alkaline reserve or buffer to retard a return to an acidic state. There are several known processes for deacidifying paper whether bound or unbound. U.S. Pat. Nos. 3,472,611; 3,703,353; 3,676,182; 3,939,091; 3,676,055; 3,969,549; and 4,318,963 are exemplary.
Unfortunately, most of these processes suffer from one or more of a number of drawbacks that have prevented their widespread acceptance. These drawbacks include high cost, toxicity, complexity of treatment, residual odor, deleterious effects on certain types of paper and inks, lack of an alkaline reserve, and the necessity of drying the book or paper to very low moisture contents before treatment.
U.S. Pat. No. 4,522,843 which issued on Jun. 11, 1985 to Robert Kundrot describes a process in which acidic cellulosic materials can be treated in a manner which obviates or minimizes many of the problems of the prior art including the necessity for drying the book or paper prior to treatment. This method can be used on cellulosics (paper) even when such paper is imprinted and bound. More particularly, the Kundrot patent demonstrates that books, imaged paper and other imaged material having a cellulose base can be preserved by treatment with alkaline particles of basic metal oxides, hydroxides or salts (hereinafter referred to as alkaline material) in an amount and for a time sufficient to increase the pH of the material and provide an alkaline buffer or reserve in the pages. The alkaline particles are deposited and adhere tightly to both the fibrous structure of the paper and on the surface.
In the past, as described in the Kundrot patent, the books were dipped vertically into a treatment medium. Following treatment, a small section of each page, adjacent the binding of a book for example, remained untreated, even after repeated dippings. Neutralization of the small section would eventually occur. The mobile acid species in the untreated areas eventually migrate across the page to the particles of basic metal oxides, hydroxides, or salts which are distributed through the cellulosic or paper web of the pages, where they are neutralized. However, this process may take a prolonged period of time until it has been completed. Thus, it is preferable to deacidify the entirety of each page of the book during the treatment process to prevent deterioration of the book. Accordingly, it is desirable to develop a method of handling the cellulosic materials during treatment which ensures that the pages of the book are treated completely by the deacidification process.
Another problem associated with the treatment of cellulosic materials was that the alkaline material was often visible as a powdery substance on the surface of pages after treatment was completed. This detracts from the appearance and utility of the treated books.
Therefore, a method of deacidification is needed which overcomes the aforementioned deficiencies of the methods used in the past and will substantially, and preferably completely, treat each page of a book or other cellulosic material without leaving a visible residue of the treating material.